Acid-Base Disturbances and Related Factors in Patients under General Anesthesia

Background: In patients undergoing surgery, acid-base imbalance during general anesthesia causes disruption in the function of cardiovascular, respiratory, musculoskeletal and the central nervous system. Since the potential complications of acid-base disturbances are serious, we decided to explore these changes and related causes so that prevention and compensation would be feasible. Methods: In this study, acid-base disruption and its causes during general anesthesia were studied in 60 patients. The patients were divided into three groups based on the location of surgery: abdominal (I), extremities (II), and head and neck (III). Body central temperature, type, and volume of injected fluids and bicarbonate (as needed) were recorded. In the second, third, and fourth hours of surgery, arterial blood gases and pH were measured. Results: The incidence and degree of metabolic acidosis in all patients were significantly related to the duration of the surgery. The number of patients with acidosis and the number of patients requiring treatment were also greater in groups I and II than in group III. Although all patients became hypothermic during the surgery, there was no significant relationship with development of acidosis. No relationship was found between the type and volume of the solution administered and development of acidosis. Conclusion: In our opinion, monitoring of acid-base status in prolonged surgeries especially in abdominal and extremity operations seems necessary.